644028480 has 84 divisors (see below), whose sum is σ = 2215199532. Its totient is φ = 171740160.

The previous prime is 644028479. The next prime is 644028481. The reversal of 644028480 is 84820446.

644028480 is a `hidden beast` number, since 644 + 0 + 2 + 8 + 4 + 8 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (644028479) and next prime (644028481).

It can be written as a sum of positive squares in 2 ways, for example, as 410305536 + 233722944 = 20256^2 + 15288^2 .

It is a super-2 number, since 2×644028480² = 829545366102220800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (644028481) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 108931 + ... + 114690.

It is an arithmetic number, because the mean of its divisors is an integer number (26371423).

Almost surely, 2^644028480 is an apocalyptic number.

644028480 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

644028480 is an abundant number, since it is smaller than the sum of its proper divisors (1571171052).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644028480 is a wasteful number, since it uses less digits than its factorization.

644028480 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 223644 (or 223631 counting only the distinct ones).

The product of its (nonzero) digits is 49152, while the sum is 36.

The square root of 644028480 is about 25377.7162093046. The cubic root of 644028480 is about 863.5782406548.

The spelling of 644028480 in words is "six hundred forty-four million, twenty-eight thousand, four hundred eighty".